74 INFECTION AND RESISTANCE 



produced by staphylococci, and with various bacterial hemolytic poi- 

 sons (tetanolysin and other bacterial hemotoxins). The result of all 

 this work has been the very important determination that susceptible 

 animals may be actively immunized both against the effects of the 

 toxin alone, as well as against the virulent bacteria themselves, by 

 systematic treatment with culture filtrates containing the toxins. 

 Since in many cases the effects of the toxins were so powerful that 

 their attenuation was desirable, Behring and others have advised the 

 addition of iodinterchlorid and other chemicals to the first in- 

 jections. 



PASSIVE IMMUNIZATION 



In the logical development of the fundamental facts regarding 

 immunization, with attention focused early on the blood and body 

 fluids as the probable carriers of immunity, it was but a rational 

 step from active immunization to the conception that such acquired 

 immunity might be transferred from a treated to a normal animal 

 by injecting blood from the former into the latter. This was prob- 

 ably the underlying thought of Toussaint's 55 early work with an- 

 thrax, in which he heated anthrax blood to 55 C. and injected it 

 into other animals, wrongly believing that the bacteria had been 

 killed by the heating. The method of Toussaint, however, was vague 

 in its conception, and in no way constitutes an example of true 

 passive immunization. The beginning was made in a purposeful 

 and clearly conceived way by Richet and Hericourt. 56 



These investigators actively immunized dogs against stapkyio- 

 cocci, and then attempted to transfer the immunity to normal rabbits 

 by injecting defibrinated blood from the immune dogs. Their suc- 

 cess was a partial one only, for reasons that we will discuss directly. 

 Reasoning similar to that of Richet and Hericourt was applied by 

 Babes and Lepp 57 to rabies immunization. When the blood of 

 rabies-immune dogs was injected into normal dogs and rabbits, and 

 these inoculated with rabies several days later, the treated animals 

 regularly survived the controls, but in one dog only was the occur- 

 rence of rabies absolutely prevented. Since their animals were nof 

 experimentally inoculated, but subjected to the more uncertain 

 method of allowing them to be bitten by a mad dog, and since the 

 series included 4 animals only (2 treated and 2 controls), Babes and 

 Lepp were unable to draw definite conclusions. The establishment of 

 passive immunization as a proved scientific fact was finally accom- 



55 Toussaint. Compt. rend, de I'acad. des sc., 1880. 



56 Richet and Hericourt. Compt. rend, de I'acad. des sc., 1888, Vol. 107, 

 p. 750. 



67 Babes and Lepp. Ann. Past., Vol. 3, 1889. 



